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POWhy don't Java, C# and C++ have ranges?
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copied!<p><a href="http://en.wikibooks.org/wiki/Ada_Programming/Types/range" rel="nofollow noreferrer">Ada</a>, <a href="http://web.mit.edu/sunsoft_v5.1/www/pascal/lang_ref/ref_data.doc.html" rel="nofollow noreferrer">Pascal</a> and many other languages support ranges, a way to subtype integers. A range is a signed integer value which ranges from a value (first) to another (last). It's easy to implement a class that does the same in OOP but I think that supporting the feature natively could let the compiler to do additional static checks.</p> <p>I know that it's impossible to verify statically that a variabile defined in a range is not going to "overflow" runtime, i.e. due to bad input, but I think that something could be done. I think about the <a href="http://en.wikipedia.org/wiki/Design_by_contract" rel="nofollow noreferrer">Design by Contract</a> approach (Eiffel) and the Spec# ( <a href="http://research.microsoft.com/en-us/projects/contracts/" rel="nofollow noreferrer">C# Contracts</a> ), that give a more general solution.</p> <p>Is there a simpler solution that checks, at least, static out-of-bound assignment at compile time in C++, C# and Java? Some kind of <a href="http://en.wikipedia.org/wiki/C%2B%2B0x#Static_assertions" rel="nofollow noreferrer">static-assert</a>?</p> <p><strong>edit</strong>: I understand that "ranges" can be used for different purpose:</p> <ol> <li>iterators</li> <li>enumerators</li> <li>integer subtype</li> </ol> <p>I would focus on the latter, because the formers are easily mappable on C* language . I think about a closed set of values, something like the music volume, i.e. a range that goes from 1 up to 100. I would like to increment or decrement it by a value. I would like to have a compile error in case of static overflow, something like:</p> <pre><code>volume=rangeInt(0,100); volume=101; // compile error! volume=getIntFromInput(); // possible runtime exception </code></pre> <p>Thanks.</p>

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